stinius said:
Just post it. Who cares if some flamers come along?
Also, if you do post it, please also post your schematic file or a picture of it. A lot of people seem to have minor variants of this circuit (e.g. one simulator file I downloaded had a quadruple output, and a resistor between the driver emitters, which does not appear in any of Dunlap's various schematics.)
In my simulations I noticed that LT Spice IV often fails to converge with a large (greater than 25V peak) input, regardless of timestep. I'm not sure why, but spice has historically had a hard time modeling transistors in saturation.
One thing I will say I like about this output stage: it has a nice high input impedance and is unlikely to load down a competently designed VAS.
stinius said:
Please do post your results. To the best of my knowledge, I have nothing to hide. If they will not Zip down to a size you can post, maybe ostripper or someone else here will let you upload them to their site.
stinius said:
Please feel free to post as you wish and if there is a concern with any comments feel free to hit the report button. Andrew can help you with that, he's well versed.
scott wurcer said:
Sometimes I am not sure how I should respond.
I can not do what you keep asking for. I can't even dress myself.
If someone building the amps can do that, after confirming they have a good build, then I am all for it.
I no longer have access to all the equipment I once had. I can still, hopefully, explain to someone how to setup and run distortion numbers on a unit. I no longer have the capability to output pretty graphs. I also no longer have any use for most of the other expensive toys in my shop. I'm not sure why I haven't gotten rid of it all already. I could use the money.
I had no idea it would be this difficult to share my design with other people.
Hi Steve,
There will always be a few who question whatever information comes along. Just ignore them, just as you do a bug that hits the windshield of a car (or truck!
). The silent majority are grateful you are taking the time to let us see what you are doing.
Personally, I think it's great that you are sharing. I do know that the interchange with the more reasonable people are very good for you as a person. Very important when you can't get out often to interact with people. I know this first hand.
There is an "ignore member" function built in. Perhaps you might feel better by invoking it?
Please Steve, continue. You may fine a few members who will build and measure your amplifier. If I lived closer to you, I would.
-Chris
There will always be a few who question whatever information comes along. Just ignore them, just as you do a bug that hits the windshield of a car (or truck!
). The silent majority are grateful you are taking the time to let us see what you are doing.Personally, I think it's great that you are sharing. I do know that the interchange with the more reasonable people are very good for you as a person. Very important when you can't get out often to interact with people. I know this first hand.
There is an "ignore member" function built in. Perhaps you might feel better by invoking it?
Please Steve, continue. You may fine a few members who will build and measure your amplifier. If I lived closer to you, I would.
-Chris
Steve Dunlap said:
Steve
Ok I will post the results, will make a zip file.
You have nothing to hide or fear.
Cheers
Stinius
Ok
Here are the results from my simulation, remember it is only simulation.
I have done some modifications to the 50W Krill amp, not many.
I have changed some transistors and the output stage is two pairs not one pair as the original design.
As you can see most of the distortion is related to the front end. So a better input / VAS stage would improve the results very much.
I have also compared the Krill with the posted THD measurements on the Ayre amp.
I know it’s not fair to compare simulations and real measurements, so it is not necessary to comment those numbers.
As you can see, Steve has a very good output stage.
BTW: before you ask, it was NO Global NFB.
Cheers
Stinius
Here are the results from my simulation, remember it is only simulation.
I have done some modifications to the 50W Krill amp, not many.
I have changed some transistors and the output stage is two pairs not one pair as the original design.
As you can see most of the distortion is related to the front end. So a better input / VAS stage would improve the results very much.
I have also compared the Krill with the posted THD measurements on the Ayre amp.
I know it’s not fair to compare simulations and real measurements, so it is not necessary to comment those numbers.
As you can see, Steve has a very good output stage.
BTW: before you ask, it was NO Global NFB.
Cheers
Stinius
Stinius: if you did your sim in LTSpice IV, could you kindly post your .asc file? Then we can all have a common reference to discuss.
anatech said:Hi Steve,
There will always be a few who question whatever information comes along. Just ignore them, just as you do a bug that hits the windshield of a car (or truck!
Personally, I think it's great that you are sharing. I do know that the interchange with the more reasonable people are very good for you as a person. Very important when you can't get out often to interact with people. I know this first hand.
There is an "ignore member" function built in. Perhaps you might feel better by invoking it?
Please Steve, continue. You may fine a few members who will build and measure your amplifier. If I lived closer to you, I would.
-Chris
Hi Chris,
I don't want to ignore any members. I just want them to understand that I simply can't do some of the things they ask for repeatedly. I must live with my physical limitations. Selling off some of my test equipment became a reality I had to face. Strange how the fancy new stuff always seems to sell most easily.
stinius said:
OK, not too embarrassing. It has been my experience that the circuit, with the posted VGS, will routinly measure below 0.01% THD at 100W output into 8 ohms. I never built a production 50W unit so I can't say how that would measure.
Steve,
I have a question that doesn't require any physical exertion to answer. What is the theory of operation of your bias scheme?
I have a question that doesn't require any physical exertion to answer. What is the theory of operation of your bias scheme?
He already posted the explanation for the operation of the bias scheme
Cool Stinius, not too shabby a set of results!
Cool Stinius, not too shabby a set of results!
But if the emitters of bias transistors tried to move apart like this suggests, more current would flow through the bias string and the base-emitter diodes of the bias transistors and turn on both of them harder.
Bias transistor conduction is controlled by their common base current which is determined by the voltage over the series connection of upper bias transistor emitter-base diode, the bias string and lower bias transistor base-emitter diode. If this voltage increases the transistors conduct harder, if it decreases they conduct less - stabilizing voltage between their emitters.
If there is "non-switching" it's either due to charge storage in outputs or leakage currents of the transistors.
The way Steve suggests Vbe increases because the transistors conduct less doesn't add up for me.
Bias transistor conduction is controlled by their common base current which is determined by the voltage over the series connection of upper bias transistor emitter-base diode, the bias string and lower bias transistor base-emitter diode. If this voltage increases the transistors conduct harder, if it decreases they conduct less - stabilizing voltage between their emitters.
If there is "non-switching" it's either due to charge storage in outputs or leakage currents of the transistors.
The way Steve suggests Vbe increases because the transistors conduct less doesn't add up for me.
traderbam said:
I see we both have handicaps. I am afraid I can't give you an answer that requires no actual thought.
Steve Dunlap said:
Steve, I don't think people are being difficult (in most cases, anyway), just inquisitive 🙂
I think once they know that they need to be patient or more helpful themselves, then they will post in that manner 🙂
All is well, I believe ... hope you are enjoying all the discussions and being part of them.
Thanks for your innovative ideas/designs 😎
🙂
traderbam said:
Hasn't that been asked earlier in the thread?
I would hate for anyone to have to repeat the same thing many times as different people around the world join a thread.
Not anything personal mind you, I just think I recall that previously addressed.
Steve Dunlap said:
It is impossible to make everyone happy. Share the design as you wish and those interested will build it. The results will speak for themselves.
People only interested in simulating the design will not be the ones sitting back relaxing to it anyway. To my knowledge this is not a "project under design for marketing" so either you are building it to listen to it or you are trying to find faults in others work to make yourself feel better.
And I do NOT mean to offend anyone (although I am sure SOMEBODY's feelings were hurt) but the man GAVE us a design after we (Carlos) tracked him down. What MORE could we ask for? 😕
Steve Dunlap said:
That's a pretty average response, more so in light of the rants over the last page or so against those who have dared to question the theory of operation and performance claims you have made for this circuit.
People here how aren’t idiots have explained more that one issue with the claimed “non-switching” nature of this design (such as that erroneous capacitor placed across the driver transistor bases), which you pretty much refuse to acknowledge.
Oh well, each to their own
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